290 DR. M. J. SCHLEIDEN ON PHYTOGENSIS. 



currence of cells floating loose in a great many plants. Finally, 

 not a single example has occurred to me of newly originated 

 cellular tissue, cambium excepted, in Avhich the cytoblasts were 

 wanting. I therefore think I am justified in supposing the pro- 

 cess above described to be the general law of formation of the 

 vegetable cellular tissue in Phanerogamia. 



My observations are much more limited with regard to the 

 Cryptogamia ; nevertheless I found the cytoblasts in the sporidia 

 of the HelveUoids, where however, on account of their great 

 transparency, they are only perceptible with very high magni- 

 fying powers and with a considerable darkening of the field. In 

 the large yellowish ceUs in the interior of the so-called anthers in 

 Chara vulgaris I have observed them. In the sporules of Mar- 

 chantia pohjmorpha I also noticed their development into cells, 

 one of which, pressing the original parietes of the sporule for- 

 wards, forms the long capillary root (Plate XV. fig. 18 — 20.). 



It is evident from the preceding that the cytoblast can never 

 lie free in the interior of the cell, but is always inclosed in the 

 cellular wall ; and in fact, as far as observation wiU allow us to 

 draw conclusions from such ticklish examinations, in such a man- 

 ner that the waU of the cell spUts into two laminae, one of which 

 passes interiorly, the other exteriorly, over the cytoblast. That 

 on the inner side is in general the most delicate, and frequently 

 only gelatinous, and is also reabsorbed at the same time with 

 the cytoblast (fig. 8, 16, 21.). Sometimes, in preparing sections, 

 they ai'e ruptured and scattered over the glass, which might lead 

 one to suppose that they were free. And probably they are 

 subsequently, on incipient reabsoi'ption, disengaged from their 

 connexion with the cellular wall, and then a slight touch may 

 suffice to disturb them from their position. The wall of the cell 

 is frequently thickened in their neighbourhood, especially where 

 they are rather globular, for instance in the pollen tube of species 

 of Orchis which has become cellular (fig. 16 and 20). 



Meyen, who should always be consulted in relation to anato- 

 mical subjects, has endeavoured in his Physiologic, vol. i. p. 45, ' 

 &c., employing in a very ingenious way his beautiful observa- 

 tions on the relations of structure in developed cells, to establish 

 the opinion that the cell is formed of spiral fibres intimately 

 superposed. My direct observation, which may easily be re- 

 peated by every one, gives, it is true, quite a different mode of 

 formation ; nevertheless I must bring the facts related by Meyen 



